A mobile device can't connect to Exchange Online by using Exchange ActiveSync

Applies to: Exchange OnlineOffice 365


A user's mobile device can't connect to Microsoft Exchange Online in Microsoft Office 365 through Microsoft Exchange ActiveSync. However, the mobile device previously could connect.


This issue can occur for many reasons. These include, but aren't limited to, the following:
  • The device can't connect to the Internet service provider (ISP) or to the Internet.
  • The device isn't set up correctly.
  • The Exchange Online mailbox server that supports the connection isn't available because of maintenance or an outage issue.


To fix this issue, follow these steps.
Step 1: Confirm that ActiveSync is enabled for the user

  1. Sign in to the Office 365 portal (https://portal.office.com) as an admin.
  2. Click Admin, and then click Exchange to open the Exchange admin center.
  3. In the left navigation pane, click recipients, and then click mailboxes.
  4. In the list of mailboxes, double-click the user, and then click mailbox features.
  5. Under Mobile Devices, take the following actions:
    1. If you see Disable Exchange ActiveSync, this means that ActiveSync is enabled for the user. Go to "Step 2: Confirm that the mobile device isn't blocked by an ActiveSync quarantine rule."
    2. If you see Enable Exchange ActiveSync, this means that ActiveSync isn't enabled for the user. Click Enable Exchange ActiveSync, click Yes when you're prompted, and then click Save.
  6. After you re-enable ActiveSync, try to set up the device again.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.


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